1. Effect of male age on fertility: evidence for the decline in male fertility with increasing age 
Mohamed A.M Hassan, M.Sc., Stephen R Killick, M.D. 
Fertility and Sterility 
Volume 79, Pages (June 2003)
DOI: /S (03)

2. FIGURE 1
The effect of increasing age, presented as age groups in years, on fecundity expressed as time to pregnancy (TTP) in months. Women’s age effect on TTP was calculated using the (A) age at conception and (B) the age at the onset of attempting to achieve pregnancy. Men’s age effect on TTP was calculated using (C) the age at conception and (D) the age at the onset of attempting to achieve pregnancy. Values in each figure represent the mean TTP for the age groups; the error bars represent the standard error of the mean. (P<.001 for all calculations.)
Hassan. Effect of male age on fertility. Fertil Steril 2003.
Fertility and Sterility  , DOI: ( /S (03) )

3. FIGURE 2
The effect of increasing age among women and men in a pregnant population on the cumulative conception rates during the first year of attempting to achieve pregnancy. (A) For women, the cumulative conception rates for each age group are as follows: <20 years old (▵), 20 to 34 years old (•), 35 to 39 years old (□), and ≥40 years old (▴). (B) For men, the cumulative conception rates for each age group are as follows: <20 years old (▵), 20 to 39 years old (•), 40 to 49 years old (□), ≥50 years old (▴). (P<.001 for both calculations.)
Hassan. Effect of male age on fertility. Fertil Steril 2003.
Fertility and Sterility  , DOI: ( /S (03) )